Chapter 7, Problem 7.86P

Water flowing at 5 kg/s and initially at 100 kPa, 20°C is to be delivered as steam at 2000 kPa, 350°C and the same flow rate to some application. The following two-step sequential process is employed to achieve the required delivered steam conditions:Step 1 – adiabatic compression to 2000 kPa, 20°C.Step 2 – constant-pressure heating to 350°C. How much work in kJ/s is needed in Step 1 and Step 2? What is the required heat transfer in kJ/s to accomplish Step 2?

A turbine, operating under steady- flow conditions, reccives 1000 kg/min of stcam. At the inlet, the pressure is 30 bar, the temperature is 400°C, the velocity At the exit, the pressure is 0.7 bar, the quality is (100%), and the velocity is 100 m/s. If the turbine produced a power output of 9300 KW. By using the energy balance of open system with sutable tables, answer the following: (a) What are the main assumptions ? (b) Calculate dh, AKe ? (c) Calculate the rate of heat transfer between the turbine and surroundings, in kW.

Problem (4.3): 1 kg of air is allowed to expand reversibly in a cylinder behind a piston in such a way that the temperature remains constant at 260°C while the yolume is doubled The piston is then moved in and heat is rejected by the air reversibly at constant pressure until the volume is the same as it was initially. Calculate the net heat flow and the overall change of entropy. Sketch the processes on a (T-S) diagram.